This invention relates generally to vacuum cleaner filter bags and more particularly to a reinforced vacuum cleaner filter bag.
Vacuum cleaner filter bags are typically formed from a blank which contains fold lines and cut-outs. The blank is folded on the specified lines and adhesive is applied during the course of the folding process whereby the filter bag is completed. Typically, such filter bags are folded into a tubular shape having closed ends with access means formed in the tubular bag for permitting passage of air into the interior of the bag so that the air can be filtered.
The specified structure of the bag may vary depending upon the type of vacuum cleaner being utilized. For example, one typical filter bag is in the shape of a conventional paper bag having a folded over edge on one end thereof and a bag bottom at the other end thereof. An opening is formed in the bag bottom which serves as the access means to permit the entry of air into the interior of the bag. The opening can then be connected to the vacuum cleaner outlet. Such a vacuum cleaner filter bag is described in U.S. Pat. No. 3,404,515.
With the aforementioned bag, a blank of sheet material is formed with the appropriate fold lines and cut-outs. Adhesive is placed along the longitudinal edge to permit the formation of an overlapped seam and the sheet is folded around to form a tubular structure. Then, the bottom is formed by appropriately folding the material. After the material is folded partway during the formation of the bottom, glue is applied in stripes and the material is then folded over to complete formation of the bottom. Transverse stripes of glue are then applied at the other end and the tubular material is folded onto itself to close off and seal the other end.
Another type of filter bag structure is the type having a long tubular body with both the upper and lower ends closed off by folding onto itself. An opening is formed in the tubular material and a separate connecting tube having an opening registered with the opening in the tubular body is connected. The connecting tube has its remote end available for connection to the vacuum cleaner outlet and the connecting tube serves as a passageway for the air into the filter bag.
This type of vacuum cleaner bag is described in U.S. Pat. Nos. 3,350,859 and 3,559,381. In this type of bag, a series of longitudinal fold lines are formed on the blank and the blank is folded around to form a tubular body having a front and rear panel and accordian side panels. Glue is provided in order to form an overlapping seam. Glue is also applied transversely at the upper and lower edges and the ends are then folded over onto itself to form a closed off cuff at the top and bottom portion. Adhesive is also placed around the registered openings to permit coupling of the connecting tube onto the tubular body.
With both aforementioned types of vacuum cleaner filter bags, as well as with other types, although the filter bag is closed and appropriate adhesive is utilized for sealing and holding the bag closed, there is a tendency for rips and tears to occur at heavily stressed portions. Typically, tears will occur at the edges where the bag has been folded over in order to close off the bag. For example, at the folded over cuff portion, there will frequently occur tears or rips. Also, in the type of bag having a bottom, at the corners of the bottom, tears and rips tend to occur. Although additional adhesive can be applied, since the adhesive is normally applied in stripes, it would necessitate applying a large amount of adhesive covering an excessive amount of area greater than the amount under stress. This would cause exposed adhesives which would be wet, tacky, and tend to stick to other adjacent bags during the course of processing.